From: Heather McIntyre <hsm2@rice.edu>
Date: Tue, 10 Oct 2023 13:42:48 +0000 (+0200)
Subject: libelf: Fix deadlock in elf_cntl
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=cdf0657d69b2b0cd0ba2609b1a0b9a25f9b9763b;p=thirdparty%2Felfutils.git

libelf: Fix deadlock in elf_cntl

	* libelf/elf_cntl.c (elf_cntl): Move rwlock_wrlock, rwlock_unlock,
	inside case switch statements.

Signed-off-by: Heather S. McIntyre <hsm2@rice.edu>
Signed-off-by: Mark Wielaard <mark@klomp.org>
---

diff --git a/libelf/elf_cntl.c b/libelf/elf_cntl.c
index 04aa9132..64087c7d 100644
--- a/libelf/elf_cntl.c
+++ b/libelf/elf_cntl.c
@@ -48,13 +48,16 @@ elf_cntl (Elf *elf, Elf_Cmd cmd)
       return -1;
     }
 
-  rwlock_wrlock (elf->lock);
+
 
   switch (cmd)
     {
     case ELF_C_FDREAD:
+     rwlock_rdlock (elf->lock);
+     int addr_isnull = elf->map_address == NULL;
+     rwlock_unlock(elf->lock);
       /* If not all of the file is in the memory read it now.  */
-      if (elf->map_address == NULL && __libelf_readall (elf) == NULL)
+      if (addr_isnull && __libelf_readall (elf) == NULL)
 	{
 	  /* We were not able to read everything.  */
 	  result = -1;
@@ -64,7 +67,9 @@ elf_cntl (Elf *elf, Elf_Cmd cmd)
 
     case ELF_C_FDDONE:
       /* Mark the file descriptor as not usable.  */
+      rwlock_wrlock (elf->lock);
       elf->fildes = -1;
+      rwlock_unlock (elf->lock);
       break;
 
     default:
@@ -73,7 +78,5 @@ elf_cntl (Elf *elf, Elf_Cmd cmd)
       break;
     }
 
-  rwlock_unlock (elf->lock);
-
   return result;
 }